• Patients with Cushing's syndrome are susceptible to opportunistic infections. Invasive fungal infections in patients with Cushing's syndrome caused by endogenous glucocorticoid excess rarely are reported, and aspergillosis occurring in this setting, to our knowledge, has not been described. Two patients with Cushing's syndrome and notably elevated levels of circulating cortisol had invasive aspergillosis develop. A patient with endogenous hypercortisolism caused by adrenal cortical carcinoma suffered a subarachnoid hemorrhage from rupture of an Aspergillus mycotic aneurysm. The other patient, who had an adrenocorticotrophic hormone-producing prostatic carcinoma, had pulmonary and disseminated aspergillosis develop. Exogenous corticosteroids are known clinically and experimentally to facilitate disseminated aspergillosis. Endogenous hypercortisolism also may be an important factor predisposing to invasive aspergillosis.